News of the investigation first became public last week, when The Associated Press reported a federal inquiry was underway. An FBI official also confirmed the inquiry to MSNBC, but declined to offer details.

On the morning of January 11, 2016, Smalls says two agents came to her home and told her they were “looking at your brother’s case.” A federal review of that case presents the possibility of the first charges in the death — the inquiry by a local prosecutor is approaching three years without any resolution.

“If they don’t find anything, I hope the FBI comes up with something,” Smalls told msnbc, adding, “It doesn’t take someone three years to come up with charges.”

The local prosecutor handling the case, Tracy Quackenbush Martin, confirmed she has been “in contact with the Department of Justice for several months,” adding she expects “a parallel investigation” focused on potential federal violations, while her inquiry “is limited to violations of state law.”

The Virginia NAACP has criticized the length of the local inquiry and called for a federal investigation into the death.

Executive Director Jack Gravely said he welcomed the federal inquiry, calling it necessary given "discrepancies" between statements about the tasing made by South Boston, Virginia police officers and what is visible in video of the incident.

One officer said Lambert grabbed her Taser and jumped up four times during the tasing — which never occurred on the video of the incident. Gravely told MSNBC he was told that a South Boston officer said the use of force was “dirty” — or unjustified — and that the local prosecutor’s inability to finish her investigation was questionable.

“Why does it take three years to investigate the death of one man in your jurisdiction — and you have a video of it?,” he asked. “Either you are incompetent, or you are hiding something, or a combination of both,” Gravely said.

Martin responded in a new statement to MSNBC, saying she understood the “urgency” many feel about the investigation, and a “desire to know the course and substance” of the inquiry, but she cannot discuss its details until it is complete.

“Mr. Gravely implies that I am withholding a final report from the public,” she added, “Nothing can be further from the truth.”

“The death of any individual merits the highest level of consideration, and that is what I have given this case,” she continued. Citing the state police investigation,

Martin added that she “chose not to make a final determination” on charges based on the state police investigation, which she noted the NAACP called it into question, and instead “sought to expand the investigation to other sources of information.”

“Demanding both speed and thoroughness is simply not realistic in this case,” Martin emphasized, “I have chosen to give greater weight to thoroughness over expediency in this weighty matter.”

The state police investigation included conflicting reports about the incident, and internal files from that “suspicious death” report, first published by MSNBC, indicate one investigator cast Martin’s approach as “indecisive.”

Lambert’s death raised a range of legal questions because he was taken into custody for medical care – not as a suspect — and was tased repeatedly while shackled in the doorway to the E.R. and again while shackled in the back of a police car. Police rules and federal guidelines bar taser use on a restrained subject. Police never took Lambert into the hospital for the medical care they had originally offered. After he broke their squad car window, they tased him repeatedly at the hospital and drove him to jail, where he died.

Several law enforcement and legal experts determined that the three officers’ use of force — discharging 20 tasings within half an hour — was excessive.

The South Boston Police Dept. has denied all wrongdoing in a civil suit about the incident.